The present invention relates generally to a unique and novel keyless entry system for operating automotive devices, such as door locks, a trunk lid lock, a glove box lid lock, steering lock devices and/or a starter motor without mechanical keys. In particular, the invention relates to a keyless entry system which is operated by means of a battery and active when a weak battery is detected to produce an alarm.
U.S. Pat. No. 4,205,325, to Haygood et al, discloses a keyless entry system for an automotive vehicle permitting a plurality of operations to be achieved from outside the vehicle by one who is knowledgeable of predetermined digital codes. Functions such as unlocking the doors of the vehicle, opening the rear trunk lid, opening a roof window, lowering the windows or programming the system with a user-preferred digital access code can all be performed by proper sequential operation of a digital keyboard mounted on the outside of the vehicle.
This and other conventional keyless entry systems require the user to accurately input the predetermined code through the keyboard. Although such keyless entry systems have been well developed and considered useful for eliminating the need for mechanical keys, a serious problem may occur when the user of the vehicle forgets the predetermined code. If the user is outside of the vehicle and the vehicle door lock device is holding the doors locked, the user cannot unlock the door locks until he remembers the predetermined code.
The present invention provides a novel and more useful system for operating the vehicle devices without an ignition key and without requiring manual entry of a predetermined code.